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I have both of those units. I use the Deltran Battery Tender for my Z4, but I just raise the hood and use the jumper cable access points. I use the Schumacher charger/maintainer on an old Cadillac that has sat literally for months at a time. Both units work fine as a maintainer. Given the cost difference (especially with the BMW-branded version of the Deltran), the Schumacher is a good deal.

1. Is the Schumacher a suitable trickle charger for a Z4? The documentation seems to indicate motorcycles, RVs, boats, and classic cars. It's a 12V charger, and the battery in the Z4 is 12V, but it's not a bike/RV/Boat or classic car (yet).

2. Even though the cigarette lighter adapter fits perfectly, I want to make sure that I'm not making a mistake connecting it to the Schumacher unit and then to the Z4.

... My biggest concerns are... Is the Schumacher a suitable trickle charger for a Z4? The documentation seems to indicate... classic cars... the Z4 is 12V, but it's not a... classic car (yet)...

Battery tenders only recognize the battery, not the vehicle it's in. I use the same battery tender for my 1997 BMW Z3 and for my 1966 BMW R27 motorcycle with 12V conversion. The battery tender does not know that one is a modern car with a big battery, and the other is a vintage motorcycle with a battery the size of a paperback. It just looks for any 12V battery to take care of, and goes to work.

I also use a motorcycle battery tender on my Z4 and it works fine (also through the jumper points as mentioned above). For a big battery like in a 4WD it might not have enough ampage, but it's certainly enough for the (relatively) small Z4 battery.

Personally though, when putting a car into storage, I prefer to disconnect the battery completely. I don't see the point in leaving it hooked up.

I also use a motorcycle battery tender on my Z4 and it works fine (also through the jumper points as mentioned above). For a big battery like in a 4WD it might not have enough ampage, but it's certainly enough for the (relatively) small Z4 battery...

It's a matter of time, not amps. A car tender is 1.25 amps and a motorcycle tender is .75 amps. Either will work fine on the other, but a .75 amp tender will just take longer to bring a large battery up to storage level. It might take a .75 amp tender many days on an SUV battery before its light turned green.

The charger will work just fine. I use a tender on my diesel pickup which has 2 very large batteries. If those batteries were dead, it would take 2 weeks to charge them up with that charger. The only thing about cigarette lighter chargers is that you need to make sure the outlet is constantly live, not switched on with the ignition. It won't work on the switched outlets very well. I have a Z3 so I don't know the electronics of your Z4.

I connected the unit to my Z4 last night, and the charging light came on. It's still on now as I type this.

I took the car out a few times this winter (when the roads were dry and snow free) to charge up the battery; when starting the car, the battery light came on so I knew that it needed to get some activity... so connecting the tender was kind of important to mitigate a dead battery. Since I bought the car used last summer and it didn't come with the radio's security code, a dead battery would be a serious PITA, even if I were to replace it.

I chose to go with the cigarette lighter attachment for two reasons:

1. Easier, to connect/disconnect.
2. The clamps that came with my unit don't spread wide enough to reach the remote terminals under the hood. Believe me, I tried this first before ordering the cig. lighter adapter, and when trying to work under the hood the wiring on the clamps just didn't have the length to be able to connect properly. I considered doing this directly on the battery itself, but decided to just make my life easier and buy the cig. adapter.

1. Is the Schumacher a suitable trickle charger for a Z4? The documentation seems to indicate motorcycles, RVs, boats, and classic cars. It's a 12V charger, and the battery in the Z4 is 12V, but it's not a bike/RV/Boat or classic car (yet).

2. Even though the cigarette lighter adapter fits perfectly, I want to make sure that I'm not making a mistake connecting it to the Schumacher unit and then to the Z4.

1. What my old Caddy and Z4 have in common is that they are both wet-cell 12V batteries. To the charger they are indistinguishable. Some cars (older Miatas and even Z4Ms) use AGM batteries which require a slightly different charging program.

2. For your cigarette lighter adapter, the only thing I would double check is polarity. Both chargers will shut off immediately if polarity is reversed.

Quote:

Originally Posted by Drexel5

I connected the unit to my Z4 last night, and the charging light came on. It's still on now as I type this.

I took the car out a few times this winter (when the roads were dry and snow free) to charge up the battery; when starting the car, the battery light came on so I knew that it needed to get some activity... so connecting the tender was kind of important to mitigate a dead battery. Since I bought the car used last summer and it didn't come with the radio's security code, a dead battery would be a serious PITA, even if I were to replace it.

I chose to go with the cigarette lighter attachment for two reasons:

1. Easier, to connect/disconnect.
2. The clamps that came with my unit don't spread wide enough to reach the remote terminals under the hood. Believe me, I tried this first before ordering the cig. lighter adapter, and when trying to work under the hood the wiring on the clamps just didn't have the length to be able to connect properly. I considered doing this directly on the battery itself, but decided to just make my life easier and buy the cig. adapter.

The Z4s don have radio codes, so you are safe there.

For me, I have found that the Battery Tender takes about 1/2-3/4 hour per day sitting to bring the battery to full charge (e.g. car sitting for 10 days, charge for 5-7 hours).

For connecting underhood with the clamps, I found that I had to tug on the clamp wires a bit to separate them further. They will separate cleanly. Since you already have the cigarette lighter adapter, I would give it a go, taking care to watch for polarity.